Grounding device for electrical wiring systems



. Ian. 2, 1934. I .J' E, MAIR 1,941,905

GROUNDING DEVICE FOR ELECTRICAL WIRING SYSTEMS Filed Dec. 5, 1950 F|G.4.0 16 n 12 n Z 18 2] I i i r 2O 7! l I 18 W (3 m m INVENTOR B Y ATTO RNEY tached. Such Patented J an. 2, 1934 PATENT OFFICE GROUNDING DEVICEFOR ELECTRICAL WIRING SYSTEMS John E; Mair, Mars, Pa., assignor toNational Electric Products vCorporation,

New York,

7 N. Y., a corporation of Delaware Application December 1930. Serial No.500,237

5 Claims.

vide means to assure the. continuity of the grounding systems. throughthe connections which are made at junctions, outlets, etc. Heretofore,one system for obtaining such grounded connections dependedupon tightlysetting up the various threaded portions of such connections.

The obtaining of the proper ground with this arrangement is entirelydependent upon the painstaking work of the installer and-,at pointswhere it is difficult to obtain access to connections, it frequentlyhappens that such connections are not set up tightly enough to assure agood ground connection.

Another means heretofore used to secure a ground connection is toprovide a grounding ring to which a grounding or bonding wire is securedand which ring is clamped between the securing members and the box to begrounded. This arrangement again depends on the connection being tightlyset up and has the same objecn .tions as previously outlined.

A further previous grounding arrangement involves the use of a bushingor securing means which contains as an integral part, a lug or screw towhich a grounding or bonding wire may be atan arrangement necessitates aduplication of the stock of such bushings or securing means in orderthat they may be marketed both with and without the lug or groundingscrew. I

The present invention has for its object the provision of a simplegrounding ring which will eliminate the necessity of duplicating stocksof existing fittings.

A further object of the present invention re- ;sides in the provision ofa grounding ring which is adapted to have direct contact with theconduit material used in the wiring system.

A further object of the present invention is to provide a ring whichwill be simple to manufacture and economical of material.

A further object of the present invention resides in the provision of anew form of ground connection which embodies the feature of a groundingring secured within an embracing bushing and cooperating with the'end ofa conduit, the ring being provided with a projecting lip portionextending without the bushing to which a ground wire may be attached.

Further and other objects will be hereinafter 5-;set forth in theaccompanying specification and claims and shown in the drawing, which byway of illustration shows what I now consider to be a preferredembodiment of the invention.

Referring to the drawing:

Figure 1 shows a plan view of a preferred form of grounding ring;

Fig.2 is a side elevational view of the ring shown in Fig. 1;

Fig. 3 is a viewsimilar to Fig. 2, but shows a terminal secured to thering to which a wire may be soldered; and.

Fig. 4 is a part sectional assembling view showing my grounding ring inuse.

In more detail in the drawing, the grounding ringis preferably made of adisk of conducting 3 material such as brass or copper and comprises anarrow band or ring 10 with an angularly projecting lip 11 which issuitably threaded at 12 to receive a screw 13 (see Fig. 2). The inneropening of ring 10 is approximately the same di- 1i,

ameter as that of the inside of the conduit with which the ring is to beused (see Fig. 4). In Fig. 3 the terminal 14 is secured to the lip 11 bymeans of the screw 13. A suitable wire 15 can be soldered to theterminal. ous that the wire 15 can be secured directly to the ring byplacing the conductor of the wire between the head of the screw 13 andthe lip 11.

In the installation of my grounding ring as is shown in Fig. 4., thering is inserted in the bushing 16 underneath the shoulder 1'7 of thebushing as shown. The lip 11 projects beyond the shoulder of thebushing. The conduit 18 is first inserted through the opening 19 of boxwall 20,

the bushing 16 is then screwed on the threaded end of the conduit 18until the band 10 of the ring is clamped between the end of the conduit18 and the shoulder 17 of the bushing. A lock nut 21 is then run up sothat the box wall 20 is securely gripped between the lock nut and theinner end of the bushing 16. A ground or bond wire 15 is then secured tothe lip 11 by means of the screw 13. It will be noted that the lip 11 ofthe grounding ring may be fabricated by turning up of the metal which ispushed out to form the inner opening of the bonding ring. Thus theprojecting lip portion may be said to be formed of metal gathered fromthe center of the ring in forming it. In this way there is a saving ofmaterial in the manufacture of the bonding ring. Furthermore byprojecting the lip 11 from the inside annular edge of the ring 10 theexterior of the ring 10 may be of circular conformation with the smoothperiphery free from projecting portions so as to be adapted to fitwithin the em- It will be obviso bracing portions of the bushing 16,which bushing 16 not only surrounds the exterior of the ring, butprojects over the top thereof as clearly shown in Fig. 10. The ring 10accordingly can be proportioned so that its periphery snugly fits theshoulder of the bushing and grounding connection surfaces may be securedat the complete outer periphery of the ring 10 to the bushing as well asthrough the upper and lower surfaces of the ring to the bushing and tothe end of the conduit 18 respectively.

It will be understood that the grounding or bonding wire may be solderedto the lip of the ring in place of being secured underneath the screwhead and that other variations of the construction may be made allwithin the scope of the present invention as defined by the appendedclaims.

What I claim is:

1. A device of the class described including a bushing provided with asleeve-like portion and an inwardly extending shouldered portion and amember within said bushing provided with an end portion disposed underthe shouldered portion, a ground connection device comprising a bandportion which peripherally fits the sleeve-like inside portion of thebushing and which has its upper and lower faces clamped by the inwardlyextending shoulder of the bushing and by the upper end portion of theaforesaid member, and a projecting lip portion from said band portionextending beyond said shouldered portion of the bushing and inaccessible position above the said shouldered portion for receiving aground wire connection.

2. A grounding ring connection device comprising a band portion providedwith a smooth external periphery free from projecting portions so thatthe ring may snugly fit within an embracing bushing, said ring alsohaving a projecting ground wire securing lip portion extending from theinner periphery of the band portion, and ground wire securing means onsaid lip portion for securing a ground wire to said ring.

3. A grounding ring comprising an annular band portion and a projectingground wire securing lip, said lip projecting from the inner annularedge of the band and being deformed out of the plane of the annular bandportion substantially as described.

4. A grounding ring comprising an annular band portion and a projectingground wire securing lip, said lip projecting from the inner annularedge of the band and being deformed out of the plane of the annular bandportion and outwardly to a point without the exterior periphery of theannular band.

5. A grounding connection adapted for use in providing a groundconnector to a conduit having a threaded end, a bushing on said threadedend having a shoulder inwardly directed over the end of the conduit, agrounding ring of conducting material clamped between said shoulder andthe end of the conduit, said ring having an integral lip portionextending therefrom from the interior of the ring and extending over theshoulder of the bushing, said lip having a ground wire securing meanscarried thereby.

JOHN E. MAIR.

